YOHO Town, YOHO Midtown & Grand YOHO Drain Services

Grand YOHO Phase 1 flats start on 6/F, directly above the podium, and YOHO Midtown also sits on five podium levels. As an inference from the design, the stack changes direction where it enters the podium, and if that bend or the horizontal run is narrowed by grease, tissue or renovation debris, the flats closest to the podium are the first to see the toilet water level rise, the floor drain overflow or a sewage smell when the floors above discharge heavily. If the toilet and floor drain react together, mostly at the morning and evening peaks, report it to the management office first so the shared stack can be checked. If only one outlet is slow, the flat's own branch pipe is the likelier cause and you can book a call-out.

Grand YOHO Towers 9 and 10 have flats numbered up to 51/F, and the tallest YOHO Midtown tower has 42 storeys above the podium. The Buildings Department explains that when an upper flat discharges a large volume, siphonage creates negative pressure in the branch pipes of flats below, strong enough to pull the water seal out of their traps; the anti-syphonage pipe or air admittance valve is there to balance that pressure. If your basin or bath gurgles when someone upstairs flushes, or the toilet water level suddenly drops and a smell follows, check whether the trap and anti-syphonage valve under the basin have been removed or replaced with the wrong type. Altering these fittings is minor works and must be done by a registered contractor.

Every YOHO Midtown flat has an environmental balcony, and most Grand YOHO flats have a cross-ventilated balcony as well as a utility platform. Floor drains in these spaces rarely take water, and none of the three estates was designed under the newer rule that uses basin or bath water to top up floor-drain seals, so the water in the trap slowly evaporates and sewer air drifts in through the balcony door or from the utility platform. The Buildings Department asks residents to top every floor drain up with roughly half a litre of water at least weekly. The sales brochure also notes that common pipes run past the balcony, utility platform or air-conditioning platform of some flats; if the smell or a leak comes from one of those common pipes rather than the drain outlet, leave it to the management office and do not box in or drill into the pipe yourself.

The kitchen appliance schedule in the Grand YOHO Phase 1 sales brochure includes a washer-dryer, the kitchen has a stainless-steel sink, and Wikipedia notes that every flat has a separate kitchen. As an inference from the design, the washing machine usually discharges into the same branch pipe as the sink. Cooking grease coats the pipe wall, lint and detergent residue from the machine build on it, and the branch pipe narrows until the sink backs up or bubbles whenever the machine empties. Start by cleaning the lint filter and checking that the machine's drain hose is not squashed or pushed in too far. If the sink is already slow in everyday use, the build-up in the branch pipe needs clearing; drain cleaner alone may not shift a mix of grease and lint.

YOHO Town was occupied in 2004 and is over 20 years old. As a general inference from its age, a good number of flats will have changed hands or been refitted, and the most common after-effects of a new bathroom or kitchen are cement slurry and tile fragments washed into floor drains, and original traps swapped out or anti-syphonage valves removed. The Buildings Department warns that unauthorised changes to the drainage system can make the water seal in a trap disappear and let foul air into the flat, and that altering traps, anti-syphonage pipes or drain positions requires a registered contractor under the Minor Works Control System. If slow draining or a smell started after the renovation, check the traps and connections of the newly fitted fixtures first.